The present invention is an improvement over the prior art for the following reasons. First, the prior art discloses a paper added with 0.5 to 1.5 wt % of water-resistant agent, such as calcium stearate or calcium palmitate, to adjust the printability of the paper. The dosage of the water-resistant agent cannot be greater, otherwise, the paper will contain too much oily material and cannot be written or printed on. However, the water-resistant agent, such as calcium stearate or calcium palmitate, used in this invention provides adhesive, molding and water-resistant effects after heating at a temperature of 115 to 170.degree. C. Therefore, at least 8 wt % of the water-resistant agent should be used to achieve the above-mentioned unexpected results.
Furthermore, the present process for manufacturing the present moldable paper board utensil is characterized by the step of mixing the pulp, surfactant, like rosin soap and water-resistant agent orderly before the refining step. With this step, the water-resistant agent can be homogeneously dispersed on the surface of the pulp, and its retention rate is also significantly increased. Before the final product is obtained, the product should be hot pressed. Thereby, the water-resistant agent will melt to provide the water-resistant effect. In other words, the subject biodegradable paper utensil and the prior art water-proof paper are quite different in process, usage and purpose.
Recently, to overcome the environmental pollution problem caused by such non-degradable disposable utensils, effort and labor have been devoted to the development of naturally degradable materials, such as degradable polymers, for manufacturing degradable food containing utensils. However, such biodegradable plastic materials are either in experimental stages or are too expensive to commercialize. Therefore, some paper utensils have been used in order to prevent the contamination of the environment. However, utensils, such as paper lunch boxes, cups, and trays, were made with milk carton paper board, a paper sheet with polyethylene layer laminated on both sides thereof. However, the polyethylene is not naturally degradable and thus causes the environmental problem.
It is therefore desirable to provide biodegradable water-resistant, moldable paper boards and molded paper utensils thereof to overcome the above-mentioned problems.